#ifndef THREADS_THREAD_H
#define THREADS_THREAD_H

#include <debug.h>
#include <list.h>
#include <hash.h>
#include <stdint.h>
#include "synch.h"

/* States in a thread's life cycle. */
enum thread_status
  {
    THREAD_RUNNING,     /* Running thread. */
    THREAD_READY,       /* Not running but ready to run. */
    THREAD_BLOCKED,     /* Waiting for an event to trigger. */
    THREAD_DYING        /* About to be destroyed. */
  };
  
/* This structure holds information about the child which is stored in the list
     of the parent
*/
struct child
{
  int pid;                    /* process id of the child */
  int status;                 /* return status of the child */
  struct list_elem childelem; /* used for list operations in the list of the
                                  parent thread structure */
};

/* This structures stores information about a file opened by a thread */
struct openedFile
{
  int fd;                     /* file descriptor associated with the file*/
  struct list_elem fileElem;  /* used to access/modify the list */
  struct file * f;            /* file pointer for the opened file*/
};

/* This structure holds the mapping information for a particular mapped page */
struct mapStruct
{
  int map_id;
  void *virtual_address;
  struct list_elem map_elem;
  struct file * f;
};

/* Thread identifier type.
   You can redefine this to whatever type you like. */
typedef int tid_t;
#define TID_ERROR ((tid_t) -1)          /* Error value for tid_t. */

/* Thread priorities. */
#define PRI_MIN 0                       /* Lowest priority. */
#define PRI_DEFAULT 31                  /* Default priority. */
#define PRI_MAX 63                      /* Highest priority. */

/* A kernel thread or user process.

   Each thread structure is stored in its own 4 kB page.  The
   thread structure itself sits at the very bottom of the page
   (at offset 0).  The rest of the page is reserved for the
   thread's kernel stack, which grows downward from the top of
   the page (at offset 4 kB).  Here's an illustration:

        4 kB +---------------------------------+
             |          kernel stack           |
             |                |                |
             |                |                |
             |                V                |
             |         grows downward          |
             |                                 |
             |                                 |
             |                                 |
             |                                 |
             |                                 |
             |                                 |
             |                                 |
             |                                 |
             +---------------------------------+
             |              magic              |
             |                :                |
             |                :                |
             |               name              |
             |              status             |
        0 kB +---------------------------------+

   The upshot of this is twofold:

      1. First, `struct thread' must not be allowed to grow too
         big.  If it does, then there will not be enough room for
         the kernel stack.  Our base `struct thread' is only a
         few bytes in size.  It probably should stay well under 1
         kB.

      2. Second, kernel stacks must not be allowed to grow too
         large.  If a stack overflows, it will corrupt the thread
         state.  Thus, kernel functions should not allocate large
         structures or arrays as non-static local variables.  Use
         dynamic allocation with malloc() or palloc_get_page()
         instead.

   The first symptom of either of these problems will probably be
   an assertion failure in thread_current(), which checks that
   the `magic' member of the running thread's `struct thread' is
   set to THREAD_MAGIC.  Stack overflow will normally change this
   value, triggering the assertion. */
/* The `elem' member has a dual purpose.  It can be an element in
   the run queue (thread.c), or it can be an element in a
   semaphore wait list (synch.c).  It can be used these two ways
   only because they are mutually exclusive: only a thread in the
   ready state is on the run queue, whereas only a thread in the
   blocked state is on a semaphore wait list. */
struct thread
  {
    /* Owned by thread.c. */
    tid_t tid;                          /* Thread identifier. */
    enum thread_status status;          /* Thread state. */
    char name[16];                      /* Name (for debugging purposes). */
    uint8_t *stack;                     /* Saved stack pointer. */
    int priority;                       /* Priority. */
    struct list_elem allelem;           /* List element for all threads list. */

    /* Shared between thread.c and synch.c. */
    struct list_elem elem;              /* List element. */
        
    //following definitions added for userprog
    struct thread *parent;              /* parent thread of current thread */
        
    int loadReturnCode;                 /* stores the return value of load
                                            used in exec () */
    int exitReturnCode;                 /* return code of the current thread */
    int childExitReturnCode;            /* return code of the child */
    int waiting_for_childid;            /* pid of the child the current thread
                                            is waiting on, if any */
    
    struct list fileOpenList;           /* list of all opened files by the 
                                            current process */
    struct list childrenList;           /* list of children for the current 
                                            process */
        
    struct semaphore waitStatus;        /* synchronization primitive between
                                            parent and child for wait () */
    struct semaphore loadStatus;        /* synchronization primitive between 
                                            parent and child for load/exec */
    struct file *processFile;           /* file pointer for holding the 
                                            descriptor of process being 
                                            executed, used to ensure deny writes
                                        */
    int fileCount;                      /* tells which file descriptor id
                                             to be returned */
                                             
    void *stack_base_address;           /* stores the base of the stack when 
                                             a new page for the stack address
                                             is created */
    bool entered_syscall_handler;       /* tells whether a page fault occured when
                                             we were processing a syscall */
    struct hash supplementary_page_table;
    struct lock supplementary_page_table_lock;    
    
    //used for mapping
    struct list mapList;
    int next_mappingId;

#ifdef USERPROG
    /* Owned by userprog/process.c. */
    uint32_t *pagedir;                  /* Page directory. */
#endif

    /* Owned by thread.c. */
    unsigned magic;                     /* Detects stack overflow. */
  };

/* If false (default), use round-robin scheduler.
   If true, use multi-level feedback queue scheduler.
   Controlled by kernel command-line option "-o mlfqs". */
extern bool thread_mlfqs;

void thread_init (void);
void thread_start (void);

void thread_tick (void);
void thread_print_stats (void);

typedef void thread_func (void *aux);
tid_t thread_create (const char *, int , thread_func *, void *);

void thread_block (void);
void thread_unblock (struct thread *);

struct thread *thread_current (void);
tid_t thread_tid (void);
const char *thread_name (void);

void thread_exit (void) NO_RETURN;
void thread_yield (void);

/* Performs some operation on thread t, given auxiliary data AUX. */
typedef void thread_action_func (struct thread *t, void *aux);
void thread_foreach (thread_action_func *, void *);

int thread_get_priority (void);
void thread_set_priority (int);
void 
updateChildStatus (struct thread *, int);

int thread_get_nice (void);
void thread_set_nice (int);
int thread_get_recent_cpu (void);
int thread_get_load_avg (void);

#endif /* threads/thread.h */
